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The Commando Frame - NOC Roadholder May 2018

Discussion in 'Norton Commando Motorcycles (Classic)' started by robs ss, May 11, 2018.

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  1. robs ss

    robs ss VIP MEMBER

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    Some, who are not NOC members, may find the following article interesting if you haven't seen it before)

    Rob
    IMG_20180512_0005.jpg IMG_20180512_0004.jpg
     
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  2. frankdamp

    frankdamp

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    Interesting reading, Rob. What was the date of that magazine article? Since I was up to my eyeballs in those problems as an N-V development engineer/test rider on both the Commando and the AJS "Stormer" it was good to see a detailed explanation.

    The AJS version of the frame got much rougher treatment than the street bikes and broke much more quickly. At one M-X meeting, I took quite a lot of 8mm movie film of the bike in action, all at 64 frames per second. We got some very useful information which led to the redesign of the top tube to insert long, skinny triangular filler pieces between two semi-circular sections. I think that design change made the frame last through the next full season without breaking. I'd emigrated to the US before the season ended.

    BTW, Dr. Bauer was of German descent and his first name was written as "Stefan". Since he was a Chemical engineer and an expert in jet engine fuels at Rolls Royce, I'm not sure of his overall influence in the design of the Commando and AJS frames, particularly as he was the Managing Director at N-V.
     
  3. wakeup

    wakeup

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    May 1, 2013
    Interesting article. When I started at NV, part of the introductory tour was into the Development shop. There was one of Dr Bauers frames there, I seem to remember that, basically, it consisted of four (40 to 50mm diameter?? it was nearly 50 years ago) large diameter tubes heading back from the steering head tube, unusual to say the least!!
    I was told that the Featherbed frame/swinging arm was torsionally compared to the Commando frame, transmission plates, swinging arm. Apparently the Commando set up was significantly lighter and much stiffer than the Featherbed. Sadly I don't remember any of the numbers.........
    cheers
    wakeup
     
  4. robs ss

    robs ss VIP MEMBER

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    Frank
    It is from the latest NOC Roadholder - No.365 May 2018
    Cheers
    Rob
     
  5. 84ok

    84ok

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  6. acotrel

    acotrel

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    Jun 30, 2012
    Engineers know everything about everything except motorcycles. When I showed my Seeley 850 to a young guy who was a section leader in a defence factory, he said 'I am impressed'. I did not say anything but I know he could not have built that bike and have it function as it needs to function. There was a paper from SAE on bike handling of which the upshot was 'we don't know what we are talking about. Most engineers these days are not motorcyclists. Phil Irving was. My feeling is that Bauer was typically arrogant.
     
  7. wakeup

    wakeup

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    May 1, 2013
    Whilst I'm not defending Dr Bauer, "Engineers know everything about everything, except motorcycles" is a bit of a sweeping statement and like most generalisations is not entirely true.
    cheers
    wakeup
     
  8. Dances with Shrapnel

    Dances with Shrapnel VIP MEMBER

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    Very interesting historical reference rob ss. Thanks for posting. When Dr. Bauer refers to the front gusset at the steering head and when I look at the illustration, I believe we are looking at the earlier “Widowmaker” frame. Also of interest is his description of the change in Center of Gravity (CoG) when the crankshaft is rotated - “heart shaped” trace. Doubt it makes any significant difference when dealing with the dynamic loading from the engine vibration and how it was mitigated through the wonderful Isolastic system.
     
  9. acotrel

    acotrel

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    Jun 30, 2012
    I have worked with too many engineers during my working life as a scientist. They usually do not handle uncertainty very well. Many do not know how to calculate a safety factor for common materials.
     
  10. acotrel

    acotrel

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    Jun 30, 2012

    A friend of mine used to rubber-mount engines in Yamaha two stroke racers to stop the frames cracking. They always seemed to go a bit slower.
     
  11. oldmikew

    oldmikew

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    Jul 25, 2015
    Maybe its just legend but I was told today that Dr Stephan Bauer did a risk assessment on frozen water up here in Derbyshire,went skating on the ice and it gave way and he drowned
     
  12. Dances with Shrapnel

    Dances with Shrapnel VIP MEMBER

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    Maybe if your friend had consulted Dr. Bauer before he tried to rubber-mount engines in Yamaha two stroke racers they would have seemed to go a bit faster.
     
  13. frankdamp

    frankdamp

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    Dr. Bauer was hired from Rolls Royce Aero Engines, directly as Managing Director, by the millionaire who rescued the Norton and AJS brand names when Associated Motorcycles went bust. I think he was of German origin, as he had a slight German accent. I'm willing to bet that most of the magazine article content came from Bob Trigg, who headed the design office at Wolverhampton.

    The final production version of the Commando still had the "Widow-maker" frame shown in the article, but it had an additional stiffener tube, maybe 1" diameter, mounted close to the bottom of the head-stock. I'd emigrated to the US before that version appeared. There was only one "large-diameter" tube in the frame design, and it ran from close to the top of the head-stock back to the cross-rail aft of the front end of the seat loop. The stiffener tube also ran between the head-stock and the cross-rail, attached near the bottom of the head-stock The stiffener tube was added by the engineers at the Plumstead Road facility in London, where the bikes were built, after the top-tube failures appeared in service.
     
  14. L.A.B.

    L.A.B. Moderator VIP MEMBER

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    Nov 20, 2004
    I believe he was actually Austrian.



    The article was published (in Motor Cycle not 'Motorcycle') in October 1967 and some months before the Commando went into production so well before the frame breakages and subsequent brace tube modification designed by Ken Sprayson of Reynolds Tubing (not the engineers at Plumstead) and why Dr. Bauer is waxing lyrical about the Commando frame design.
     
  15. davamb

    davamb

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    Nov 11, 2008
    As a scientist, you probably read Scientific American, but if you also have a copy of the latest American Scientist, have a read of the article about Engineers v Scientists:
    https://www.americanscientist.org/article/through-the-lens-of-the-big-bang-theory
    I've never watched the show, but I did find the article amusing.

    And perhaps you could also explain
    • what the maximal number of engineers is that you should work with in your life,
    • how engineers should be handling uncertainty rather than actively working to avoid it and
    • what percentage are incapable of performing this essential calculation.
     
  16. robs ss

    robs ss VIP MEMBER

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    A doctor tells a woman that she has only six months to live. He advises her to marry a Scientist and move to Toledo.

    
The woman asks, "Will this cure my illness?"

    
"No," replies the doctor, "but it will make six months seem like a very, very long time."
     
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  17. davamb

    davamb

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    Sure I've heard that same joke with "engineer" instead of "scientist", but then perhaps also "accountant" and half a dozen other professions.
    Apologies, meant eliminate it.
     
  18. acotrel

    acotrel

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    Jun 30, 2012
    When you ask engineers about safety factors most say 'we think of a number and double it'. For steel that gives a good result in the construction industry. Many engineers don't seem to know that safety factors for materials are usually a percentage of the 0.1% proof stress (the limit of elasticity) and are based on probability. I've worked with many engineers and most have the mindset that you plug in a number and get an answer. The danger lies in them getting answers from scientists' black boxes and never doing an error analysis.
     
  19. acotrel

    acotrel

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    There are no scientific facts because every 'fact' has a probability associated with it. All engineering is based upon science, so there is always uncertainty. In some aircraft applications, materials are stressed to 95% of their 0.1% proof stress. You only die once - that is certainty.
     
  20. acotrel

    acotrel

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    Jun 30, 2012
    I would have thought that a sensible engineering approach would be to build a prototype and test it to destruction, then base your configuration management on it ? I once worked in a factory where every item in a batch of product was a prototype. We had the same British management culture and hierarchies of workers.
     
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